It is known to provide directional drilling devices which provide directional drilling by means of a drilling head which has an angled cutting or drilling device thereon, the angled device being monitorable in respect to its orientation about the axis of the drill. Change in direction of the drill is achieved by ceasing or preventing rotation of the drill bit when said angle device is in a desired orientation and then pushing forward the drill such that the angled device causes the drill to deviate from its current course. Drilling can then be recommenced with the drill head being pushed forward in the desired new direction.
Directional drilling (also referred to as boring, thrusting and horizontal directional drilling (HDD) is a technology which allows services such as power cables, ducts, water pipes, gas lines, drainage pipes, etc, to be placed underground without the need to cut open the ground surface as is required in cut and cover methods. The drill gains its directional ability through the use of an angled steering blade on the drill head. Immediately behind the drill head is a transmitter (sonde) which relays information to an above ground operator, such information may include how deep the drill head is, the direction in which the drill is heading and the orientation of the drill head such as the angle it is pointing up or down.
Such devices are normally bulky and incorporate means to rotate and push forward or advance the drill bead as well as means to rotate it. It is also known to provide means to extend the drill such as a set of rods which are screwed into each other to provide additional length to the drill. The power requirement of such a device are somewhat high and as these devices incorporate the source of power the devices are large. This limits the use of the device in that it is common for drilling to be required substantially horizontally or parallel to the surface of the ground from a distance beneath the surface of the ground. Thus since the abovementioned device must rest on ground level the drill must be angled in from the surface of the ground such that it levels off at the required depth. The drills as aforementioned are of course flexible to some degree however flexibility is limited therefore to the angle at which the drill enters the ground. This means that the drilling unit itself must be positioned some distance back from the point at which the level drilling commences. Obviously this is inconvenient and may in some cases limit drilling. It may in other cases mean that neighbouring land must be encroached upon and as the ultimate length of the drill usable by such a device is limited, the length of useful drilling may also be somewhat lirmited. There is also a need for apparatus which can be used in situations when the pit or hole that is possible or preferable is somewhat smaller than the abovementioned apparatus. For example it is often the case when drilling under a road that the grass strip or verge beside the footpath is very narrow. It would be useful to have drilling apparatus which can be used in a pit which can be dug in this grass verge without having to remove or disturb the footpath or road. However a drawback of such a drilling apparatus could be that the drill rods utilised would also have to be relatively compact. This would limit the efficiency of drilling as the drill requires the attachments of drill rods one behind the other.
There is therefore a need for drilling apparatus which can be used in a configuration in which longer drill rods can be utilised therefore the apparatus itself is long but can be converted to a form in which the drilling apparatus itself is more compact.